The present invention relates to hydroxamate compounds which are inhibitors of histone deacetylase. The inventive compounds are useful as pharmaceuticals for the treatment of proliferative diseases.
Reversible acetylation of histones is a major regulator of gene expression that acts by altering accessibility of transcription factors to DNA. In normal cells, histone deacetylase (HDA) and histone acetyltrasferase together control the level of acetylation of histones to maintain a balance. Inhibition of HDA results in the accumulation of hyperacetylated histones, which results in a variety of cellular responses.
Inhibitors of HDA have been studied for their therapeutic effects on cancer cells. For example, butyric acid and its derivatives, including sodium phenylbutyrate, have been reported to induce apoptosis in vitro in human colon carcinoma, leukemia and retinoblastoma cell lines. However, butyric acid and its derivatives are not useful pharmacological agents because they tend to be metabolized rapidly and have a very short half-life in vivo. Other inhibitors of HDA that have been widely studied for their anti-cancer activities are trichostatin A and trapoxin. Trichostatin A is an antifungal and antibiotic and is a reversible inhibitor of mammalian HDA. Trapoxin is a cyclic tetrapeptide, which is an irreversible inhibitor of mammalian HDA. Although trichostatin and trapoxin have been studied for their anti-cancer activities, the in vivo instability of the compounds makes them less suitable as anti-cancer drugs. There remains a need for an active compound that is suitable for treating tumors, including cancerous tumors, that is highly efficacious and stable.
The present invention provides efficacious deacetylase inhibitor compounds that are useful as pharmaceutical agents having the formula (I): 
wherein
R1 is H, halo, or a straight chain C1-C6 alkyl (especially methyl, ethyl or n-propyl, which methyl, ethyl and n-propyl substituents are unsubstituted or substituted by one or more substituents described below for alkyl substituents);
R2 is selected from H, C1-C10 alkyl, (e.g. methyl, ethyl or xe2x80x94CH2CH2xe2x80x94OH), C4-C9 cycloalkyl, C4-C9 heterocycloalkyl, C4-C9 heterocycloalkylalkyl, cycloalkylalkyl (e.g., cyclopropylmethyl), aryl, heteroaryl, arylalkyl (e.g. benzyl), heteroarylalkyl (e.g. pyridylmethyl), xe2x80x94(CH2)nC(O)R6, xe2x80x94(CH2)nOC(O)R6, amino acyl, HONxe2x80x94C(O)xe2x80x94CHxe2x95x90C(R1)-aryl-alkyl- and xe2x80x94(CH2)nR7;
R3 and R4 are the same or different and independently H, C1-C6 alkyl, acyl or acylamino, or R3 and R4 together with the carbon to which they are bound represent Cxe2x95x90O, Cxe2x95x90S, or Cxe2x95x90NR8, or R2 together with the nitrogen to which it is bound and R3 together with the carbon to which it is bound can form a C4-C9 heterocycloalkyl, a heteroaryl, a polyheteroaryl, a non-aromatic polyheterocycle, or a mixed aryl and non-aryl polyheterocycle ring;
R5 is selected from H, C1-C6 alkyl, C4-C9 cycloalkyl, C4-C9 heterocycloalkyl, acyl, aryl, heteroaryl, arylalkyl (e.g. benzyl), heteroarylalkyl (e.g. pyridylmethyl), aromatic polycycles, non-aromatic polycycles, mixed aryl and non-aryl polycycles, polyheteroaryl, non-aromatic polyheterocycles, and mixed aryl and non-aryl polyheterocycles;
n, n1, n2 and n3 are the same or different and independently selected from 0-6, when n1is 1-6, each carbon atom can be optionally and independently substituted with R3 and/or R4;
X and Y are the same or different and independently selected from H, halo, C1-C4 alkyl, such as CH3 and CF3, NO2, C(O)R1, OR9, SR9, CN, and NR10R11;
R6 is selected from H, C1-C6 alkyl, C4-C9 cycloalkyl, C4-C9 heterocycloalkyl, cycloalkylalkyl (e.g., cyclopropylmethyl), aryl, heteroaryl, arylalkyl (e.g., benzyl, 2-phenylethenyl), heteroarylalkyl (e.g., pyridylmethyl), OR12, and NR13R14;
R7 is selected from OR15, SR15, S(O)R16, SO2R17, NR13R14, and NR12SO2R6;
R8 is selected from H, OR15, NR13R14, C1-C6 alkyl, C4-C9 cycloalkyl, C4-C9 heterocycloalkyl, aryl, heteroaryl, arylalkyl (e.g., benzyl), and heteroarylalkyl (e.g., pyridylmethyl);
R9 is selected from C1-C4 alkyl, for example, CH3 and CF3, C(O)-alkyl, for example C(O)CH3, and C(O)CF3;
R10 and R11 are the same or different and independently selected from H, C1-C4 alkyl, and xe2x80x94C(O)-alkyl;
R12 is selected from H, C1-C6 alkyl, C4-C9 cycloalkyl, C4-C9 heterocycloalkyl, C4-C9 heterocycloalkylalkyl, aryl, mixed aryl and non-aryl polycycle, heteroaryl, arylalkyl (e.g., benzyl), and heteroarylalkyl (e.g., pyridylmethyl);
R13 and R14 are the same or different and independently selected from H, C1-C6 alkyl, C4-C9 cycloalkyl, C4-C9 heterocycloalkyl, aryl, heteroaryl, arylalkyl (e.g., benzyl), heteroarylalkyl (e.g., pyridylmethyl), amino acyl, or R13 and R14 together with the nitrogen to which they are bound are C4-C9 heterocycloalkyl, heteroaryl, polyheteroaryl, non-aromatic polyheterocycle or mixed aryl and non-aryl polyheterocycle;
R15 is selected from H, C1-C6 alkyl, C4-C9 cycloalkyl, C4-C9 heterocycloalkyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl and (CH2)mZR12;
R16 is selected from C1-C6 alkyl, C4-C9 cycloalkyl, C4-C9 heterocycloalkyl, aryl, heteroaryl, polyheteroaryl, arylalkyl, heteroarylalkyl and (CH2)mZR12;
R17 is selected from C1-C6 alkyl, C4-C9 cycloalkyl, C4-C9 heterocycloalkyl, aryl, aromatic polycycles, heteroaryl, arylalkyl, heteroarylalkyl, polyheteroaryl and NR13R14;
m is an integer selected from 0 to 6; and
Z is selected from O, NR13, S and S(O),
or a pharmaceutically acceptable salt thereof.
The compounds of the present invention are suitable as active agents in pharmaceutical compositions that are efficacious particularly for treating cellular proliferative ailments. The pharmaceutical composition has a pharmaceutically effective amount of the present active agent along with other pharmaceutically acceptable exicipients, carriers, fillers, diluents and the like. The term pharmaceutically effective amount as used herein indicates an amount necessary to administer to a host to achieve a therapeutic result, especially an anti-tumor effect, e.g., inhibition of proliferation of malignant cancer cells, benign tumor cells or other proliferative cells.